Inverse analysis for determining the reinforced concrete flexural stiffness of a structure under strong compression

Abstract

In general, the determination of internal forces along the transverse sections of a piece is made assuming the structure is in its undeformed position. This represents a 1st order theory where the deformations undergone by the piece are neglected. However, when the deformations are considered, the internal forces are no longer proportional to the external forces and the problem then requires a 2nd order theory. The problem worsens when the material is non-linear. Concrete reinforcement structures subjected to high normal effort show both, geometric and physical nonlinearities. The stiffness of bars with a geometric effect is resolved analytically and numerically. There is a need to establish therefore the flexural stiffness to be used. In this work, this is obtained by inverse analysis from the frequency of a real structure in conjunction with a numerical model.